9 memcached_callback_get, memcached_callback_set - Get and set a callback
17 C Client Library for memcached (libmemcached, -lmemcached)
28 #include <memcached.h>
31 memcached_callback_set (memcached_st *ptr,
32 memcached_callback_t flag,
36 memcached_callback_get (memcached_st *ptr,
37 memcached_callback_t flag,
38 memcached_return_t *error);
47 libmemcached(3) can have callbacks set key execution points. These either
48 provide function calls at points in the code, or return pointers to
49 structures for particular usages.
51 memcached_callback_get() takes a callback flag and returns the structure or
52 function set by memcached_callback_set().
54 memcached_callback_set() changes the function/structure assigned by a
55 callback flag. No connections are reset.
57 You can use MEMCACHED_CALLBACK_USER_DATA to provide custom context if required for any
61 MEMCACHED_CALLBACK_CLEANUP_FUNCTION
63 When memcached_delete() is called this function will be excuted. At the
64 point of its execution all connections have been closed.
68 MEMCACHED_CALLBACK_CLONE_FUNCTION
70 When memcached_delete() is called this function will be excuted. At the
71 point of its execution all connections have been closed.
75 MEMCACHED_CALLBACK_PREFIX_KEY
77 You can set a value which will be used to create a domain for your keys.
78 The value specified here will be prefixed to each of your keys. The value can not
79 be greater then MEMCACHED_PREFIX_KEY_MAX_SIZE - 1 and will reduce MEMCACHED_MAX_KEY by
80 the value of your key. The prefix key is only applied to the primary key,
81 not the master key. MEMCACHED_FAILURE will be returned if no key is set. In the case
82 of a key which is too long MEMCACHED_BAD_KEY_PROVIDED will be returned.
86 MEMCACHED_CALLBACK_USER_DATA
88 This allows you to store a pointer to a specifc piece of data. This can be
89 retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st
90 will copy the pointer to the clone.
94 MEMCACHED_CALLBACK_MALLOC_FUNCTION
96 DEPRECATED: use memcached_set_memory_allocators instead.
100 MEMCACHED_CALLBACK_REALLOC_FUNCTION
102 DEPRECATED: use memcached_set_memory_allocators instead.
106 MEMCACHED_CALLBACK_FREE_FUNCTION
108 DEPRECATED: use memcached_set_memory_allocators instead.
112 MEMCACHED_CALLBACK_GET_FAILURE
114 This function implements the read through cache behavior. On failure of retrieval this callback will be called.
115 You are responsible for populating the result object provided. This result object will then be stored in the server and
116 returned to the calling process. You must clone the memcached_st in order to
117 make use of it. The value will be stored only if you return
118 MEMCACHED_SUCCESS or MEMCACHED_BUFFERED. Returning MEMCACHED_BUFFERED will
119 cause the object to be buffered and not sent immediatly (if this is the default behavior based on your connection setup this will happen automatically).
121 The prototype for this is:
122 memcached_return_t (\*memcached_trigger_key)(memcached_st \*ptr, char \*key, size_t key_length, memcached_result_st \*result);
126 MEMCACHED_CALLBACK_DELETE_TRIGGER
128 This function implements a trigger upon successful deletion of a key. The memcached_st structure will need to be cloned
129 in order to make use of it.
131 The prototype for this is:
132 typedef memcached_return_t (\*memcached_trigger_delete_key)(memcached_st \*ptr, char \*key, size_t key_length);
142 memcached_callback_get() return the function or structure that was provided.
143 Upon error, nothing is set, null is returned, and the memcached_return_t
144 argument is set to MEMCACHED_FAILURE.
146 memcached_callback_set() returns MEMCACHED_SUCCESS upon successful setting,
147 otherwise MEMCACHED_FAILURE on error.
155 To find out more information please check:
156 `https://launchpad.net/libmemcached <https://launchpad.net/libmemcached>`_
164 Brian Aker, <brian@tangent.org>
172 memcached(1) libmemcached(3) memcached_strerror(3)